Quasiturbine > Product > QT5LSC Steam


Quasiturbine QT5LSC Steam - 12 kW
(A 5 litres displacement per revolution)

8900 US$ (see purchase order form below)
Air freight available worldwide.
(Custom exempted within North America NAFTA zone).

(Check for « on the shelf » inventory...)


Air demo at only 1/4 bar (4 psi).

Fan demo at 4 psi (1/4 bar), too much torque for this strong man!

Quasiturbine Has No Vane

Unlike vane pumps, which vane extension is important and against which the pressure acts to generate the rotation, the Quasiturbine contour seals have an imperceptible extension and the rotation does not result from pressure against these seals. Since the cylindrical (or oval) stator of vane devices has a radius of curvature greater than the rotor, the two surfaces (rotor - stator) cannot reach a close fit at top dead center (TDC), while the surfaces of both the rotor and stator of the Quasiturbine fit exactly against one another to produce a high compression ratio. This is why QT is efficient (less pressure charging losses), and this is why there is no vane combustion engine. Quasiturbine publishes « efficiency data ».

QUASITURBINE Hand Rotation Test
QT5LSC (5 litres) Expander up to 12 kW under 4 bar (60 psi)


QT.6LSC (shown here) without the differential and the central shaft.
Quasiturbine Model QT5LSC has a volume of 600 cc per chamber,
and swept 8 chambers per revolution (4 on the top, 4 on the bottom),
which totalized 4,8 litres per revolution.

Quasiturbine Uniflow Characteristic

In most reciprocating piston engines, the steam reverses its direction of flow at each stroke (counter-flow). By entering and exhausting the cylinder by the same port, the cylinder valve and walls are cooled by the passing exhaust steam, while the hotter incoming admission steam is wasting some of its energy in restoring the temperature. Some energy is further lost in reversing the motion momentum of the mass of steam within the piston. The aim of the piston uni(directional)flow is to remedy this defect by providing an exhaust port at the end of the stroke, making the steam flowing only in one direction, but has the inconvenience of recompressing some residual cylinder steam. Quasiturbine is a uniflow engine, with the further advantage of not recompressing any residual steam, resulting in superior energy efficiency. Recompressing residual steam means some reversibility losses, and the pressure increases makes a substantial restriction to the initial steam flow into the chamber, not to ignore the truncated cycle near bottom dead center - None of this with the Quasiturbine.

QT5LSC Product Description

The Steam Quasiturbine unit is very similar to the pneumatic one, except for thermal dilatation provision, lubrication and corrosion consideration. Each chamber has a 600 cc maximum volume, and the motor expands 8 chambers per revolution:

Displacement: Total = 8 x 600 cc = 5 litres intake per revolution.
Intake Volumetric Flow Rate = Engine displacement x RPM
Cylindrical outside about 16" (~40.6 cm) in diameter excluding peripherals.
Thickness 5" (~12.7 cm) excluding shaft and peripherals.
The casing and rotor are made of metal (no aluminum at this time).
Power shaft: 1 1/2-inch (~3.81 cm) diameter throughout.
2 intake ports 1" male NPT pipe threads.
2 exhaust ports 2" male NPT pipe threads.
Weight (all metal) about 150 pounds (70 Kg).
Simple in-line lubrication.
Silencer is not provided.
Not optimized as compressor.

Present typical limitations under proper lubrication:
     - Intake pressure: 60 psi (4 bar) peak.
     - Revolution: 600 rpm.
     - Block temperature: Under 150 °C (300 °F) (steam can be hotter?)
     - Torque (2009 version and later):
             Up to 250 N-m (200 pound-foot) peak (with no step down gearbox).
     - Power 12 kW (15 HP) peak
     - Pressure-flow energy conversion: +/- 80 % of theoretical single-stage
       (optimum across the range - no off-peak penalty)

Maximum Temperature Control: Provision for thermal expansion is for now limited to a rotor temperature of 150 C (300 F). This is generally not a concern with a water saturated steam source up to 60 psi.

Hydraulic and Condensate : It is best to remove the condensate in the steam line before starting and continuously if necessary (This could increase the overall system energy efficiency). This steam Quasiturbine can handle saturated steam, but it must not be use with incompressible fluid (liquid hydraulic mode) - When possible, avoid excessive internal liquid condensation and do not flowed with lubricant. This unit can however be used in pneumatic mode.

Quasiturbine Model QT5LSC steam
Usable with intake pressure from 1 to 60 psi (4 bar) peak!

Not being mass produced, Quasiturbines are like precious « Ferrari »,
while the « energy cost » to run less efficient equipments may lead to no overall saving.
Among the new emerging technologies like
hybrids, hydrogen, fuel cell, PV solar, in-wheel motor, power windmill, nuclear thermal...
the Quasiturbine is by far the least expensive innovation to familiarize with!

Youtube Video Channel Quasiturbine
Technical Paper: Large-Scale Steam-powered Quasiturbine Engine Options

QT5LSC Typical Characteristics

QT5LSC theoretical main characteristics can be approximated from 3 parameters:

  • Instantaneous maximum torque for 2 opposed working chambers is
        = 64 + 64 = 130 N-m / bar (3.2 + 3.2 = 6.4 pound-foot / psi).
    The average torque is 65 % of the instantaneous maximum, which is 84 N-m / bar (4.0 pound-foot / psi) differential effective pressure through the motor, assuming no truncated intake);

  • The RPM revolution within reasonable range up to 600 rpm and the Intake Volumetric Flow Rate up to 2,5 m3/min. (600 cc x 8 chambers per revolution x rpm, assuming no truncated intake);

  • The power output up to 12 kW peak, which is proportional to the product: Torque X rpm.

Typical value given as indication only. May vary from one QT to another.

QT5LSC Steam characteristics are roughly similar to the Air Motor.
This graph is from a QT5LSC Air Motor
at 500 rpm and up to 60 psi (4 bar), and is given as an indication.
Perfect « single-stage theoretical expander curve » is shown for comparison.
Ratio of the 2 curves is +/- 80%
(optimum across the range - no off-peak penalty)

Steam consumption: For most positive displacement engine, the Intake Volumetric Flow Rate is the displacement time the rpm, which gives for the QT5LSC:
     = 5 litres x 500 rpm = 2,5 cubic meter per minute.
QT reacts to gas or steam volume (not mass) given as the « Intake Volumetric Flow Rate - IVFR » which depend only of displacement and rpm, not of pressure, nor of power. At higher power, pressure is higher and mass flow is higher, but the Volumetric Flow stay unchanged.

Mass flow conversion involve assumptions and rules of practice that each customer may decide for himself in relation to his design. Calculation uses Mollier diagram www.chemicalogic.com/download/mollier.html,
or online « Steam Table Calculator » like:
If the design does not capture the condensate at engine intake, the mass flow could in practice be higher with no additional power output, while IVFR stay unchanged. Liquid other than water could provide better efficiency at low steam temperature.

Efficiency reminder: Specific steam flow in kg/kW-h is not a comparison efficiency criteria between different turbines, because there is much less energy invested in 1 kg of steam at 4 bar and 150 C, that there is in 1 kg of steam at 30 bar and 300 C. For efficiency comparison, one must look at the turbine energy output versus the energy content within the kg of steam?

Theoretical Output Power Extrapolation: Pressure increases both the rpm and the torque. Since the power is proportional to the product of rpm  X  torque, the power output is roughly proportional to the square of the pressure.  Increasing the pressure by 3 fold would then increase the power by 9 times!  (15 kW at 4 bar would theoretically become 140 kW at 12 bar  - or  -  25 HP at 60 psi would theoretically become 240 HP at 200 psi). This is of course outside the operational range of the present machines...

Expander Efficiency

Expanders expand the gas of a reservoir, but not necessarily the gas within the expander. The efficiency is a ratio expressed in %. It is used to evaluate an equipment result in relation to either the incoming energy (Semi absolute efficiency - when for example for gasoline engine: energy extraction, transportation and refining are discarded), either in relation to a partial form of energy (relative efficiency), or in relation to the result of an other equipment or reference theory (comparative efficiency). To further complicate the situation, different engines with same efficiency on bench test will lead to different efficiency applications (in mobility for example, due to weight and gearbox requirement). No correct efficiency interpretation is possible without knowing detail calculation. Consequently, it is not possible to optimized simultaneously an expander for maximum power and maximum efficiency, a choice must be done.

The efficiency is generally in relation to the task an equipment is attempting to accomplish, and in the present context all « single-stage expanders » can conveniently be compared to the « single-stage expander theoretical model (without intake cut-off) », which is simply a piston making work under pressure, while moving in an infinitely long cylinder (which is a useful reference):

Theoretical Single Stage (TSS) Calculation:

British units: (See theoretical line on the British units graph)
Power (HP) = Pressure (psi) X Volumetric Flow Rate (VFRcfm) / 229
(As an example: 1 HP = 7.63 VFRcfm at 30 psi)
Metric units: (See theoretical line on the SI units graph)
Power (kW) = Pressure (bar) X Volumetric Flow Rate (VFRm3/min.) X 1.70
(As an example: 1 kW = 0.29 VFRm3/min at 2 bar)

Devices are not all equally efficient when attempting to match this theoretical piston-cylinder model, but Quasiturbine does it (with no intake cut-off) at +/- 80 % of the perfect theoretical single-stage (with potential improvements up to 95 %). To reach such a level of comparative efficiency, other concepts need to run at nominal power only, or to use intake cut-off techniques. Such techniques are adaptable to the Quasiturbine as well, for an overall top performance.

Note: There is more intrinsic energy in the compressible incoming flow (energy accumulating in the infinitely long cylinder as the piston moves) that single-stage expanders are not attempting to recover (it is not within their tasks), and which end up in the exhaust. Additional recovery would require cut-off intake valve and multi-stages (QT?) expanders, but at a much reduced machine specific power density (larger expander and higher cost).

Selecting a high efficiency engine is a good start, but other system components and thermodynamic cycles also impact the global system efficiency, which should not be confused with the engine component efficiency.

Comparing Quasiturbine to Vane Motor

Since the cylindrical (or oval) stator of vane devices has a radius of curvature greater than the rotor, the two surfaces (rotor - stator) cannot reach a close fit at top dead center (TDC), while the surfaces of both the rotor and stator of the Quasiturbine fit exactly against one another to produce a high compression ratio. This is why QT is efficient (less pressure charging losses). Several manufacturers are offering quality products based on Vane Motor concept. As a matter of preliminary comparison (assuming intake pressure near the effective internal pressure), here are some typical data of Quasiturbine versus a GAST air product (calculated under same running pressure):

Quasiturbine QT.6LSC under 4 bar (59 psi) and 500 rpm: 1.7 kW // 2.3 HP
Detail: www.quasiturbine.com/EProductQT75SCPneumatic.htm
Intake Volumetric Flow Rate (IVFR) = 0.3 IVFRm3/min // 10.6 IVFRcfm
Effective Displacement: 0.3 IVFRm3/min / 500 rpm = 600 cc // 36.6 po3 per revolution
Consumption: Free air* = 1.5 m3/min of free air // 53 cfm of free air
(* Estimated at 4 bar (59 psi) as 5 times the IVFR of 0.3 m3/min).
Consumption Specific = 0.88 m3/min-kW of free air // 23 cf/min-HP of free air
Theoretical Single Stage Power (TSS) = 4 bar X 0.3 m3/min X 1.70 = 2.04 kW
Theoretical Single Stage Power (TSS) = 59 psi X 10.6 IVFRcfm / 229 = 2.74 HP
QT Performance: 1.7 kW / 2.04 kW = 2.3 HP / 2.74 HP = 83 % of TSS

GAST 4AM Vane motor under 7 bar (103 psi) and 3000 rpm: 1.3 kW // 1.7 HP
Detail: www.gastmfg.com/pdf/airmotor/specsht/4AM.pdf
(Notice that this motor accepts air only - no steam)
Intake Volumetric Flow Rate (IVFR)* = 0.25 IVFRm3/min // 9.2 IVFRcfm
(* Estimated at 7 bar (103 psi) as 8 times less the flow of 2.0 m3 free air /min).
Effective displacement: 0.25 IVFRm3/min / 3000 rpm = 83 cc // 5.1 po3 per revolution
Consumption: Free air = 2 m3 free air /min // 70 cfm of free air
Consumption Specific = 1.53 m3 free air /min-kW // 41 cf/min-HP of free air
Theoretical Single Stage Power (TSS) = 7 bar X 0.25 X 1.70 = 3.0 kW
Theoretical Single Stage Power (TSS) = 103 psi X 9.2 / 229 = 4.0 HP
GAST Performance: 1.3 kW / 3.0 kW = 1.7 HP / 4.0 HP = 43 % of TSS

From the energy reversibility (heat lost) point of view, the difference is even greater, as one consumes its air volume at 7 bar (100 psi), while the QT consumes it at only 4 bar (60 psi). In conclusion, the Quasiturbine concept (without intake cut-off) operates at 80 % of the Theoretical Single Stage (TSS) Power, compared to 40 % for Vane Motor concept (even when using some intake cut-off saving), with QT potential to reaches 95 % under high mechanical tolerances. Furthermore, QT operates in the most demanding conditions of high displacement, low pressure and high torque. Consequently, the Quasiturbine air/steam concept exceeds substantially the relative efficiency of Vane Motor concepts, which is consistent with the vane loading chamber volume lost. For many applications, there is little or no benefit to use vane air motor when the pressured fluid consumption is the dominant cost factor.

QT Steam Lubrication

As for piston steam engine, periodic oil needs to be injected into the motor intakes steam flow. One possibility is oil injection within one of the intake port using a small pulsed pump (electrical or pneumatic). An other more simple way is to keep an oil reservoir pressurized (with air?) slightly over the QT intake pressure, and to simply control the oil flow through a needle valve.

The grade of recommended steam cylinder oil for these conditions is ISO 460 which contains 4% tallow oil. This is the grade of oil that the “ride-on” locomotive community uses. It is generally available in 5 gallons, but Sulphur Springs Steam Models sales@sssmodels.com provides it in quart cans. Chevron USA has a relatively new steam cylinder oil on the market that is lighter in viscosity than ISO 460 by about half (1103 SUS vs. 2335 SUS @ 100 F). Other steam oil may do as well, search " steam cylinder oil" on the web for local suppliers. It does not require much oil, and it can be re-circulated.

Never use motor oil or inappropriate lubricant. Never use oil with additive like antifriction, because large air flow or steam oxidized the oil and precipitate the additives in « glue like product », as it will oxidize and degrade into solid or viscous material under steam contact. If this happen, attempt cleaning the engine with a glass of kerosene in the intake, while turning the engine slowly by hand. Re-oil properly.

Feed Line Capacity

Flow velocity near a piston valve is always impressive, and it is not different with the Quasiturbine intake ports. To sustain 500 rpm in a 5 litres displacement QT5LSC, the intake flow rate must be (5 litres X 500 rpm) = 2.5 m3 / min.. Knowing that a 1 inch diam. tubing contains 0.5 litres / meter long, this correspond to a flow velocity in the tube of :
(2500 litres / min.) / (0.5 litre / m)  =  85 m / s or 300 km / h
Could be half, considering that the Quasiturbine has 2 intakes which could be feed individually. Velocity near the intake ports will be even higher. Consequently, such a relatively small tubing must be quite short (or act as a limiting safety factor to protect the unit?). Notice that once the pressurized fluid gets into the engine, the flow velocity reduces to match the tangential rotor speed, which is:
(engine perimeter = 50 cm) X 500 rpm = 8.5 m / s = 30 km / h
and flow speed increases again into the exhaust, which must show minimum restriction.

Good example of minimum exhaust flow restriction
after air expansion (few meters).
This preserves pressure differential and full power of the QT.
An appropriate steam condenser close to the exhaust port
could also be a valid solution.
Across an expander, the mass flow stays constant,
but the volumetric flow does not.

A good set-up require a short and generous size feed line and exhaust line.

Sealing the Quasiturbine

As delivered, the Quasiturbine has no pretention to be a sealed machine, and in particularly at the shaft bearings.

Because Quasiturbine can be used with a multitude of gases (some environmentally sensitive), and considering the multitude of seals available, it is up to the owner to apply if needed, its proper sealing solution to the system (Look in Search Engine Image for « Axial Radial Shaft Seal » or « Replacement Cartridge Mechanical Seal »). Some seals cost less that 10 $ to buy, but high temperature seal could cost more. General info at www.skf.com/files/889495.pdf .

While thin wall enclosure is an ultimate solution for critical situation, stuffing box (made of a simple outside washer bolted to the engine block) with Graphite Coating Packing Sealants could often be an acceptable straight forward solution.

QT5LSC Steam - Purchase Order (PO) Form

To : Quasiturbine Tronçonneuses
Casier/Code/Porte 2804 - 3535 Papineau
Montréal Québec H2K4J9
514-527-8484  Fax: 514-527-9530
Associated website : www.quasiturbine.com

Quasiturbine model QT5LSC Steam (12 kW peak)
with rotating central differential and shaft,
is intended for integration research, demonstration and projects.
To be used only under competent supervision.
Guaranty is limited to replacement (pick-up) of defective parts.

Sale done FOB Montréal, Québec Canada
Price including Canadian local sale taxes when applicable
but not the shipping (pick-up) and custom fees
(NAFTA Exempted?) H.S. # 8413.81:               8900.00 US$
Money rate conversion at http://fr.finance.yahoo.com/m3

The web page
is an integral part of the present purchase order
and constitute the terms and conditions accepted by the buyer.

          Authorized Officer                              Date: ______________

Company Name: __________________________

Shipping address: _________________________


Phone: ____________________     Fax: _______________________



Package: Weight: 120 kg / 260 pounds.
Size: 60 cm X 60 cm X 52 cm high / 24 X 24 X 20 inches height.

Email the form to info@quasiturbine.com or fax to 514-527-8484.
An invoice will follows with payment instructions.
(Terms: Pick-up or shipping the day the funds transfer is received).


Electric Generator

A 12 poles AC generator would be a good RPM match with Quasiturbine.
For information (not necessarily recommendation), see also the following:


The PTO Generator considered by APUQ on their website at

A fraction of the engine output is lost in the electric conversion process.
Example: 8 kW for 900 $ at
Also available up to 150 kW in European standard (ex. Winco)

IDEAS? (Not tested possibilities...)

Rotary Pressure Regulator:
What about an "energy recovery rotary pressure regulator" ? An interesting application of the steam Quasiturbine is to recover the high pressure energy at pressure reduction stations. Instead of using a conventional cooling station, a steam Quasiturbine will rotate under the pressure differential and the flow will be controlled by the rpm, i.e. the torque applied on the Quasiturbine shaft. This way, the Quasiturbine can transform the pressure differential into useful mechanical work to run pump, compressor, ventilator, electricity generator or locally convert the energy in high grade heat. Because conventional turbines can not be widely modulated in rpm and load, they are not suitable for gas flow and pressure control, while the Quasiturbine is essentially a closed valve at zero rpm (subject to appropriate construction), and has high efficiency at all torque and all flow rpm. All experimental demonstration has to be done only by steam experts and under all current rules and regulations.

ORC (Organic Rankine Cycle):
Engine suitable for ORC (Organic Rankine Cycle) in Solar, Geothermal and Waste Heat Recovery.

QT Operation

It is the buyer and/or operator responsibility to comply with all applicable national
and local laws and rules, including those on security and pressurized products.
In several countries 1 bar (15 psi) is considered as high pressure!

  • It is the buyer and/or operator responsibility to comply with all applicable national and local laws and rules, including those on security and pressurized products. Current research lab precaution and procedure must apply.
    Steam is dangerous, and steam qualification personnel is a must.

  • Familiarize yourself well beforehand with the Quasiturbine technology (see the associated site at: www.quasiturbine.com ).

  • Remove the condensate in the steam line before starting and continuously if necessary, to insure smooth running. Important: Use only degasified liquid to make vapor or steam. See http://en.wikipedia.org/wiki/Degasification

  • For optimum performance, the feed line must be well balanced between the two intake ports, which must be done by ending the line passed the 2 T by an accumulator (buffer) tank (minimum 20 litres), on which the pressure gage can be located.

  • Make it turns gradually (without abrupt acceleration).

  • Ensure that the rotor is adequately lubricated (steam oil only: search "steam cylinder oil" on the web for local suppliers). (Never use oil with additive like antifriction, because large air flow or steam oxidized the oil and precipitate the additives in glue like product fatal to the Quasiturbine operation).

  • Ensure that the hoses and fasteners (particularly the flexible ones) are of quality and well anchored.

  • It is recommended not to exceed 600 RPM and/or 4 bars (60 psi) at the pressure gauge when with load, half without load. 150 C max. No free running at more than 20 psi.

  • Avoid flow restriction at exit.

  • Intake steam must be reasonably clean, and always with degassed fluid.

  • Silencer is not provided.

QT Safety Precautions

  • These unit must be operated under the constant supervision of qualified adults. Heat protection should be use at all time.

  • Anchor the unit well before each start-up.

  • Never exceed the limits and suggested conditions of operation.

  • Wearing safety glasses, mask and fastened hair is recommended.

  • The demonstration room must be well ventilated.

  • Check the tightening of the bolts and adapters. Be aware of the rupture
    or the decoupling of any of the flexible hoses.

  • Have a distant valve at hand to cut the air/steam flow as needed.

  • Particularly during breaking-in under compressed air, it can happen that the rotor stops at a dead point, and refuses to turn when the pressure is applied. This situation is unstable and call for urgent pressure release. In absence of pressure, slightly turn the rotor with the central shaft and pressurize it again...

  • During the demonstration, nothing should approach the central zone of the rotor; make observations at a distance of 50 cm (20 po.) or more.

  • Always remain vigilant and careful!

QT Sale Details


  • Sale and operation are restricted to adults only.

  • Steam (not necessarily water)-air-nitrogen (less than 60 psi).
    No liquid hydraulic mode.

  • Additional parts of replacement can be ordered by owners.


  • The Purchasers release the manufacturer from all responsibilities relative with the use.

  • Guaranty of the manufacturer is limited to the replacement (pick-up) of the defective parts.

  • The present document and conditions must be transferred to the chain of future owners of the unit.

  • If there is intellectual propriety risk, the manufacturer can simply refund and not deliver.

  • The purchasers accept the present page as part of the purchase order agreement and invoice.


  • The price includes the applicable local sale taxes if required, but not the shipping (pick-up) and custom fees.

  • The insurances and customs fees are the responsibility of the purchaser.

  • As possible, shipping (pick-up) will be made on schedule following the reception of the payment, or according to the production capability of the moment (Check for « on the shelf » inventory...).

  • Failure of the buyer to make final payment or take delivery of the unit within 3 months of the notice of completion will be interpreted as an abandon of the product without compensation.


(Manufacturer under a privileged QT-BLADES supply license agreement)
Casier/Code/Porte 2804, 3535 Ave Papineau, Montréal Québec H2K 4J9 CANADA
(514) 527-8484      Fax (514) 527-8484
Associated website www.quasiturbine.com   info@quasiturbine.com

Subject to changes without notice - January 7, 2015